1. Field of the Invention
This invention relates to a method of making a shaped article from one or more integrated multi-layered sheets.
2. Description of the Related Art
Especially for use in transport means, such as aircraft, automobiles and trains, a search has long been made for materials which are both light in weight and possess high stiffness, impact resistance and strength. In this regard, it has heretofore been proposed to make sandwich constructions consisting of a completely or partly hollow core having provided thereon a fibrous synthetic layer. Such sandwich constructions possess clear advantages with regard to mechanical properties and weight when compared with massive materials. A commercially sold product consists of, e.g., a honeycomb structure having provided on its surface a thin fibrous layer.
Although the prior art sandwich constructions possess clear advantages from a viewpoint of mechanical properties, in practice they are rather difficult to shape, especially where there is a great deal of variation in shape or where the shape is very complex. In such cases, very difficult and time-consuming operations are required, and often times the desired form cannot in fact be made.
It is proposed in Canadian patent 1,184,106 to use a sandwich material consisting of a core of a foam material having provided on its two surfaces a layer consisting of a fibrous structure impregnated with a mixture of epoxide and hardener being in the B-stage. This material can be shaped in a mold or press and hardened to obtain a product having the desired form.
With this type of material the problem occurs that the deformation can take place only once and is not reversible. Consequently, it is not possible to shape a standard panel or reshape another article to specific forms, requirements or situations. In addition, thermosetting materials such as epoxy are susceptible to aging, resulting in deterioration in physical properties over time. There is thus a need in the art for a structural material which is light in weight, possesses good mechanical properties, and is capable of undergoing multiple deformations.